弗化カルシウムに対する海産生物の感受性

Abstract

It is well known that the treated waste effluents from aluminum metallurgical plants contain calcium fluoridel1) in concentrations of 16 to 17 ppm2) These effluents usually run into public waters, mostly into coastal waters in Japan, where various types of fishing grounds are located. However, no report is yet available concerning the susceptibility of marine organisms to calcium fluoride6, 8), in spite of the urgent necessity for predicting damages which may be brought about by the new factories that are now being con-structed on seaside areas. This paper, thus, deals with the susceptibility of a certain important sea alga, Porphyra tenera and four marine fishes, Chaenogobius annularis, Chrysophrys major, Halichoeres poecilopterus and Fugu niphobles to calcium fluoride. Susceptibility was also tested using a certain species of shrimp, Metapenaopsis barbata and one kind of clam, Tapes philippinarum. After a 30 day-culture at 10°C in artificial sea water8, 4) under 9 hours a day exposure to 6, 000 Lux of day light fluorescent lamps, it became clear that calcium fluoride gel, ranging from 12 to 376 ppm as F, did not influence adversely and to any appreciable extent the growth of Porphyra tenera. During the 4 day test period in natural sea water, with concentrations of calcium fluoride gel ranging from 13 to 232 ppm as F and at temperatures of 26 to 29°C, it was also observed that all the tested animals survived without any apparent damage. These tell us that calcium fluoride gel has no noticeable toxicity to marine organisms, probably due to the extreamely low concentrations of fluoride ion in the test solutions, as calculated from the solubility product of calcium fluoride and the concentration of calcium ion in the natural sea water used.